Machine and method for processing of printed circuit boards by immersion in transversely flowing liquid chemical

Abstract

An apparatus for chemically treating the surfaces of printed circuit board work pieces (PCBWP's) includes a tank for holding a bath of the chemical treatment liquid. A receiving device is provided for receiving the PCBWP's from a conventional transport conveyor in a horizontal orientation, and immersing the PCBWP's into the bath in a substantially vertical orientation. A conveyor device in the tank is configured to hold the PCBWP's in the vertical orientation and to move them face-on through the liquid bath while a substantially uniform transverse flow of fresh liquid is provided between the work pieces. Another conveyor device receives the PCBWP's and elevates them out of the bath in the vertical orientation, subsequently returning them to a horizontal orientation for delivery to a conventional transport conveyor.

We claim: 
     
       1. Apparatus for chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said apparatus comprising: receiving means for receiving a PCBWP in a horizontal orientation and moving the PCBWP to a substantially vertical orientation;   tank means for holding a bath of chemical treatment liquid;   immersion means for moving the PCBWP in the substantially vertical orientation from said receiving means into said bath of chemical treatment liquid;   conveyor means submerged in said bath of chemical treatment liquid for supporting and moving the PCBWP in the substantially vertical orientation horizontally along said tank substantially perpendicularly to the plane of the PCBWP;   elevator means for receiving the PCBWP from said conveyor means and elevating the PCBWP in said substantially vertical orientation upwardly out of said bath of chemical treatment liquid.   
     
     
       2. The apparatus of claim 1 wherein said apparatus further includes fluid flow means for maintaining a substantially uniform transverse flow of said treatment liquid from side to side of said tank while the PCBWP's are submerged therein. 
     
     
       3. The apparatus of claim 2 wherein said fluid flow means for maintaining a substantially uniform transverse flow of said treatment liquid from side to side of said tank includes a pair of opposed manifolds each disposed at a respective side of said tank and extending along the length thereof and vertically an extent substantially equal to a length dimension of said PCBWP, each of said pair of manifolds defining a respective array of apertures opening between an interior of said manifold and said tank, and liquid pumping means interconnecting said pair of manifolds for receiving liquid via said respective array of apertures from said tank into one of said pair of manifolds and delivering this liquid pressurized to the other of said pair of manifolds for flow therefrom via said array of respective apertures then across said tank as a substantially uniform flow field and to the one manifold. 
     
     
       4. The apparatus of claim 1 wherein said receiving means includes a tilting mechanism pivotally disposed above said tank, said tilting mechanism defining a gap in a first position horizontally aligned with a delivery conveyor for receiving a PCBWP therefrom in a horizontal orientation into said gap with a leading end edge thereof stopped against a blocking member of said tilting mechanism, said tilting mechanism pivoting to a second position at least substantially 90° from said first position with the PCBWP in said vertical orientation and with said leading end edge thereof being lowermost and disposed toward said treatment liquid. 
     
     
       5. The apparatus of claim 1 wherein said conveyor means comprises a continuous conveyor belt. 
     
     
       6. The apparatus of claim 1 further comprising repositioning means for repositioning the PCBWP from said elevator means, from the substantially vertical orientation to a substantially horizontal orientation, for conveyance generally away from said tank means. 
     
     
       7. The apparatus of claim 1 further comprising means for flopping the PCBWP elevated by said elevator means to a horizontal orientation for conveyance away from said tank means. 
     
     
       8. Apparatus for chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said apparatus comprising: receiving means for receiving a PCBWP in a horizontal orientation and moving the PCBWP to a substantially vertical orientation;   tank means for holding a bath of chemical treatment liquid;   immersion means for moving the PCBWP in the substantially vertical orientation from said receiving means into said bath of chemical treatment liquid;   conveyor means submerged in said bath of chemical treatment liquid for supporting and moving the PCBWP in the substantially vertical orientation horizontally along said tank substantially perpendicularly to the plane of the PCBWP;   elevator means for receiving the PCBWP from said conveyor means and elevating the PCBWP in said substantially vertical orientation upwardly out of said bath of chemical treatment liquid;   wherein said receiving means includes a tilting mechanism pivotally disposed above said tank, said tilting mechanism defining a gap in a first position horizontally aligned with a delivery conveyor for receiving a PCBWP therefrom in a horizontal orientation into said gap with a leading end edge thereof stopped against a blocking member of said tilting mechanism, said tilting mechanism pivoting to a second position at least substantially 90° from said first position with the PCBWP in said vertical orientation and with said leading end edge thereof being lowermost and disposed toward said treatment liquid;   wherein said immersion means includes said blocking member of said receiving means being movably carried upon said tilting mechanism, said stop member including an actuator feature engagable with an actuator block of said tank upon said tilting mechanism reaching said second position to move said blocking member away from said end edge of the PCBWP, allowing the PCBWP to drop of its own weight edge-first into said treatment liquid.   
     
     
       9. The apparatus of claim 8 wherein said immersion means further includes said tank at one end thereof including a guide member defining an angulated guide surface extending downwardly into said tank and toward which said tilting mechanism in said second position thereof generally directs the PCBWP edge-first as the latter drops from said tilting mechanism into said bath of treatment liquid, and a liquid spray means immersed in said treatment liquid and spaced from said guide member and opposite thereto with respect to a place of entry of the PCBWP into said treatment liquid, said liquid spray means providing a plurality of liquid jets directed downwardly and toward said guide member and urging the PCBWP into engagement with said guide surface of said guide member to slide therealong as the PCBWP sinks of its own weight into said treatment liquid. 
     
     
       10. The apparatus of claim 9 wherein said liquid spray means includes a spray bar immersed in said treatment liquid adjacent to an upper surface thereof and spaced from said guide member opposite to said place of entry of the PCBWP's from said tilting mechanism in said second position thereof into said treatment liquid. 
     
     
       11. The apparatus of claim 9 wherein said conveyor means includes a chain of links having laterally extending teeth in pairs spaced apart to define a laterally extending groove aligning with a lower edge of said guide member, said groove receiving a lower edge of the PCBWP as the latter sinks into said treatment liquid by its own weight along said guide surface, said pair of spaced apart teeth engaging and supporting the PCBWP in a substantially vertical orientation within said bath of treatment liquid, and means for advancing said chain of links from one end of said tank toward the opposite end thereof with the PCBWP in face-on orientation relative to movement thereof through said treatment liquid, whereby movement of the PCBWP face-on through said treatment liquid urges the latter through any through holes or apertures of the PCBWP. 
     
     
       12. The apparatus of claim 11 wherein said conveyor means includes plural such chains of links each having laterally extending teeth in pairs spaced apart to define a respective laterally extending groove aligning with a lower edge of said guide member, said grooves of each of said plural chains of said conveyor means aligning laterally with one another, whereby a lower edge of a PCBWP wide enough to engage more than one of said plural chains of links is received at said lower edge thereof into two or more of said grooves to be supported therein by said pairs of teeth in cooperation. 
     
     
       13. The apparatus of claim 11 wherein said means for advancing said chain of links from one end of said tank toward the opposite end thereof with the PCBWP in face-on orientation relative to movement thereof through said treatment liquid includes a pair of laterally extending shafts disposed one adjacent to said one end of said tank and the other adjacent to said opposite end of said tank, said pair of laterally extending shafts each carrying a respective one of a pair of tandem sprockets, said chain of links being trained over and drivingly engaging said tandem sprocket pair, and power drive means drivingly connecting with one of said pair of laterally extending shafts. 
     
     
       14. The apparatus of claim 13 wherein said chain of links is formed into a loop trained about said tandem sprocket pair, a guide plate extending between said pair of laterally extending shafts and having an upper surface slidably supporting an upper span of said looped chain of links. 
     
     
       15. The apparatus of claim 9 wherein said conveyor means includes: a horizontal chain of links having laterally extending teeth in pairs spaced apart to define a laterally extending groove aligning with a lower edge of said guide member, said groove receiving a lower edge of the PCBWP as the latter sinks into said treatment liquid by its own weight along said guide surface, said pair of spaced apart teeth engaging and supporting the PCBWP in a substantially vertical orientation within said bath of treatment liquid;   a pair of laterally-extending horizontally-spaced shafts disposed one adjacent to said one end of said tank and the other adjacent to said opposite end of said tank, said pair of horizontally-spaced shafts each carrying a respective one of a pair of tandem sprockets, said chain of links being formed into a loop trained about said pair of tandem sprockets, a guide plate extending between said pair of horizontally-spaced shafts and having an upper surface slidably supporting an upper span of said looped chain of links;   said elevator means including a second chain of links extending in a generally vertical direction from adjacent said other shaft upwardly out of said bath of treatment liquid to a third shaft spaced vertically above said other shaft, said second chain of links including spaced apart block members each carrying a respective one of a plurality of generally L-shaped clips, said L-shaped clips each defining a respective recess into which a lower edge of a PCBWP is receivable to support the latter, said other shaft and said third shaft each carrying a respective one of another pair of tandem sprockets, and said second chain of links being looped and trained over said another pair of tandem sprockets to drivingly engage the latter, and power drive means drivingly connecting with said third shaft;   whereby movement of the PCBWP on said conveyor means face-on through said treatment liquid urges the latter through any through holes or apertures of the PCBWP.   
     
     
       16. The apparatus of claim 15 wherein said conveyor means includes plural such horizontal chains of links, said elevator means similarly including plural second chains of links extending from said other shaft upwardly out of said bath of treatment liquid to said third shaft, and said plural horizontal chains of links of said conveyor means interdigitating at said other shaft with said plural second chains of links of said elevator means. 
     
     
       17. Apparatus for chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said apparatus comprising: receiving means for receiving a PCBWP in a horizontal orientation and moving the PCBWP to a substantially vertical orientation;   tank means for holding a bath of chemical treatment liquid;   immersion means for moving the PCBWP in the substantially vertical orientation from said receiving means into said bath of chemical treatment liquid;   conveyor means submerged in said bath of chemical treatment liquid for supporting and moving the PCBWP in the substantially vertical orientation horizontally along said tank substantially perpendicularly to the plane of the PCBWP;   elevator means for receiving the PCBWP from said conveyor means and elevating the PCBWP in said substantially vertical orientation upwardly out of said bath of chemical treatment liquid;   wherein said elevator means for receiving the PCBWP from said conveyor means and elevating the PCBWP in said substantially vertical orientation upwardly out of said bath of chemical treatment liquid includes a chain of links extending in a generally vertical direction from adjacent an end of said conveyor means upwardly out of said bath of treatment liquid, said chain of links including spaced apart block members each carrying a respective one of a plurality of generally L-shaped clips, said L-shaped clips each defining a respective recess into which a lower edge of a PCBWP is receivable to support the latter, and means for moving said chain of links upwardly out of said bath of chemical treatment liquid.   
     
     
       18. The apparatus of claim 17 wherein said means for moving said chain of links upwardly out of said bath of chemical treatment liquid includes a pair of laterally extending vertically spaced shafts disposed one adjacent to said opposite end of said tank at a respective end of said conveyor means to receive PCBWP's therefrom and the other above an upper surface of said bath of chemical treatment liquid, said pair of vertically spaced shafts each carrying a respective one of a pair of tandem sprockets, and said chain of links being trained over and drivingly engaging said tandem sprocket pair, and power drive means drivingly connecting with one of said pair of vertically spaced shafts. 
     
     
       19. Apparatus for chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said apparatus comprising: receiving means for receiving a PCBWP in a horizontal orientation and moving the PCBWP to a substantially vertical orientation;   tank means for holding a bath of chemical treatment liquid;   immersion means for moving the PCBWP in the substantially vertical orientation from said receiving means into said bath of chemical treatment liquid;   conveyor means submerged in said bath of chemical treatment liquid for supporting and moving the PCBWP in the substantially vertical orientation horizontally along said tank substantially perpendicularly to the plane of the PCBWP;   elevator means for receiving the PCBWP from said conveyor means and elevating the PCBWP in said substantially vertical orientation upwardly out of said bath of chemical treatment liquid;   wherein said elevator means further includes means for returning a PCBWP from said substantially vertical orientation to a horizontal orientation and delivery of the PCBWP onto a conveyor for transport thereof, said means for returning including said L-shaped clips supportingly engaging a lower edge of a PCBWP as said clips rotate around an upper one of said tandem sprockets, thereby to arcuately move said PCBWP into a horizontal orientation with a "flopping" motion generally about the lower edge of the PCBWP.   
     
     
       20. Apparatus for chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said apparatus comprising: receiving means for receiving a PCBWP in a horizontal orientation and moving the PCBWP to a substantially vertical orientation;   tank means for holding a bath of chemical treatment liquid;   immersion means for moving the PCBWP in the substantially vertical orientation from said receiving means into said bath of chemical treatment liquid;   conveyor means submerged in said bath of chemical treatment liquid for supporting and moving the PCBWP in the substantially vertical orientation horizontally along said tank substantially perpendicularly to the plane of the PCBWP;   elevator means for receiving the PCBWP from said conveyor means and elevating the PCBWP in said substantially vertical orientation upwardly out of said bath of chemical treatment liquid;   wherein said receiving means and said immersion means includes a receiving and immersion conveyor, said receiving and immersion conveyor including a vertically and horizontally spaced pair of laterally extending shafts, each one of said pair of shafts carrying a respective one of a pair of tandem sprockets, a chain of links including block members each carrying a clip member defining a gap, said chain of links being formed into a loop trained over said pair of tandem sprockets so that a leading edge of a PCBWP in a horizontal orientation is receivable into said gap, power drive means for circulating said looped chain of links about said tandem sprockets, said chain of links circulating about said pair of tandem sprockets so that a PCBWP in said horizontal orientation is receivable at a leading edge thereof into said gap of a clip at an upper one of said pair of vertically and horizontally spaced shafts, said clip rotating about said upper shaft with said chain of links to lever said PCBWP about said upper shaft into a vertical orientation, and said chain of links including a span descending angularly into said bath of chemical treatment liquid and carrying said PCBWP downwardly in said substantially vertical orientation to immerse the latter in said chemical treatment liquid.   
     
     
       21. Apparatus for chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said apparatus comprising: receiving means for receiving a PCBWP in a horizontal orientation and moving the PCBWP to a substantially vertical orientation;   tank means for holding a bath of chemical treatment liquid;   immersion means for moving the PCBWP in the substantially vertical orientation from said receiving means into said bath of chemical treatment liquid;   conveyor means submerged in said bath of chemical treatment liquid for supporting and moving the PCBWP in the substantially vertical orientation horizontally along said tank substantially perpendicularly to the plane of the PCBWP;   elevator means for receiving the PCBWP from said conveyor means and elevating the PCBWP in said substantially vertical orientation upwardly out of said bath of chemical treatment liquid;   wherein said conveyor means includes: a horizontal chain of links having laterally extending teeth in pairs spaced apart to define a laterally extending groove aligning with a lower edge of said guide member, said groove receiving a lower edge of the PCBWP as the latter sinks into said treatment liquid by its own weight along said guide surface, said pair of spaced apart teeth engaging and supporting the PCBWP in a substantially vertical orientation within said bath of treatment liquid;   a pair of laterally-extending horizontally-spaced shafts disposed one adjacent to said one end of said tank and the other adjacent to said opposite end of said tank, said pair of horizontally-spaced shafts each carrying a respective one of a pair of tandem sprockets, said chain of links being formed into a loop trained about said pair of tandem sprockets, a guide plate extending between said pair of horizontally-spaced shafts and having an upper surface slidably supporting an upper span of said looped chain of links; and power drive means drivingly connecting with said horizontally-spaced pair of shafts;   said receiving means and said immersion means including a receiving and immersion conveyor, said receiving and immersion conveyor including a third shaft spaced both vertically and horizontally with respect to said one of said horizontally-spaced pair of shafts of said conveyor means; each one of said one shaft and said third shaft carrying a respective one of another pair of tandem sprockets, another chain of links including block members each carrying a clip member defining a gap, said another chain of links being formed into a loop trained over and drivingly engaging said another pair of tandem sprockets so that said chain of links and said another chain of links are drivingly connected via said one shaft and so that a leading edge of a PCBWP in a horizontal orientation is receivable into said gap of a clip on said another chain of links as said clip is situated atop said third shaft, and said another chain of links circulating about said pair of tandem sprockets so that a PCBWP in said horizontal orientation and received at a leading edge thereof into said gap of a clip at said third shaft levers said PCBWP about said third shaft into a vertical orientation, and said another chain of links including a span descending angularly into said bath of chemical treatment liquid to said one shaft and carrying said PCBWP downwardly in said substantially vertical orientation to immerse the latter in said chemical treatment liquid.     
     
     
       22. The apparatus of claim 21 wherein said conveyor means includes plural such horizontal chains of links, said receiving and immersion conveyor similarly including plural such another chain of links extending from said third shaft downwardly into said bath of treatment liquid to said one shaft, and said plural horizontal chains of links of said conveyor means interdigitating at said one shaft with such plural another chain of links of said receiving and immersion conveyor. 
     
     
       23. Apparatus for chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said apparatus comprising: receiving means for receiving a PCBWP in a horizontal orientation and moving the PCBWP to a substantially vertical orientation;   tank means for holding a bath of chemical treatment liquid;   immersion means for moving the PCBWP in the substantially vertical orientation from said receiving means into said bath of chemical treatment liquid;   conveyor means submerged in said bath of chemical treatment liquid for supporting and moving the PCBWP in the substantially vertical orientation horizontally along said tank substantially perpendicularly to the plane of the PCBWP;   elevator means for receiving the PCBWP from said conveyor means and elevating the PCBWP in said substantially vertical orientation upwardly out of said bath of chemical treatment liquid;   wherein said conveyor means comprises a continuous conveyor belt;   wherein said conveyor means includes spaced teeth on said conveyor belt defining grooves therebetween for receiving therein a lower end of the PCBWP.   
     
     
       24. Apparatus for chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said apparatus comprising: receiving means for receiving a PCBWP in a horizontal orientation and moving the PCBWP to a substantially vertical orientation;   tank means for holding a bath of chemical treatment liquid;   immersion means for moving the PCBWP in the substantially vertical orientation from said receiving means into said bath of chemical treatment liquid;   wherein said conveyor means includes spaced slots for receiving lower ends of the PCBWPs and conveying them generally across said tank means;   conveyor means submerged in said bath of chemical treatment liquid for supporting and moving the PCBWP in the substantially vertical orientation horizontally along said tank substantially perpendicularly to the plane of the PCBWP;   elevator means for receiving the PCBWP from said conveyor means and elevating the PCBWP in said substantially vertical orientation upwardly out of said bath of chemical treatment liquid;   wherein said conveyor means includes receiving slots for receiving a lower end of a PCBWP and conveying it generally across said tank means.   
     
     
       25. Apparatus for chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said apparatus comprising: receiving means for receiving a PCBWP in a horizontal orientation and moving the PCBWP to a substantially vertical orientation;   tank means for holding a bath of chemical treatment liquid;   immersion means for moving the PCBWP in the substantially vertical orientation from said receiving means into said bath of chemical treatment liquid;   conveyor means submerged in said bath of chemical treatment liquid for supporting and moving the PCBWP in the substantially vertical orientation horizontally along said tank substantially perpendicularly to the plane of the PCBWP;   elevator means for receiving the PCBWP from said conveyor means and elevating the PCBWP in said substantially vertical orientation upwardly out of said bath of chemical treatment liquid;   wherein said elevator means includes means for receiving therein a lower end of the PCBWP and for lifting the PCBWP out of said bath.   
     
     
       26. Apparatus for chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said apparatus comprising: receiving means for receiving a PCBWP in a horizontal orientation and moving the PCBWP to a substantially vertical orientation;   tank means for holding a bath of chemical treatment liquid;   immersion means for moving the PCBWP in the substantially vertical orientation from said receiving means into said bath of chemical treatment liquid;   conveyor means submerged in said bath of chemical treatment liquid for supporting and moving the PCBWP in the substantially vertical orientation horizontally along said tank substantially perpendicularly to the plane of the PCBWP;   elevator means for receiving the PCBWP from said conveyor means and elevating the PCBWP in said substantially vertical orientation upwardly out of said bath of chemical treatment liquid;   wherein said elevator means includes a substantially vertical endless conveyor belt.   
     
     
       27. The apparatus of claim 26 wherein said elevator means includes a plurality of PCBWP holders spaced along a length of said conveyor belt. 
     
     
       28. An apparatus for chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said apparatus comprising: a tank holding a bath of chemical treatment liquid, said tank having an entrance end and a discharge end;   a continuous conveyor belt submerged in said bath and having receiving slots;   depositing means for receiving a PCBWP in a horizontal orientation, and depositing the PCBWP in a substantially vertically orientation down into said bath and into one of said receiving slots and at said entrance end;   a substantially vertical conveyor having a plurality of receivers for receiving a lower end of the PCBWP at the tank discharge end conveyed thereto by said conveyor belt, and lifting the PCBWP up and generally out of said bath; and   moving means for moving the PCBWP lifted by said vertical conveyor to a substantially horizontal orientation for conveyance generally away from said tank.   
     
     
       29. The apparatus of claim 28 wherein said depositing means drops the PCBWP down into the receiving slot. 
     
     
       30. The apparatus of claim 28 wherein said receivers comprise spaced clips. 
     
     
       31. The apparatus of claim 28 wherein said moving means flips the PCBWP over to the substantially horizontal orientation. 
     
     
       32. The apparatus of claim 28 further comprising fluid flow means for maintaining a substantially uniform transverse flow of the chemical treatment liquid from one side of said tank to another, while the PCBWP is on said conveyor belt. 
     
     
       33. A method of chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said method comprising the steps of: repositioning a PCBWP from a horizontal orientation to a substantially vertical orientation in a chemical treatment liquid bath and onto a conveyor belt submerged in the bath;   conveying via the conveyor belt the PCBWP in the substantially vertical orientation face-on through the bath along a line substantially perpendicular to the plane of the PCBWP; and   after said conveying, lifting the PCBWP out of the bath.   
     
     
       34. The method of claim 33 wherein said conveying utilizes the face-on movement to cause movement of the chemical treatment liquid through any apertures or holes penetrating through the PCBWP. 
     
     
       35. The method of claim 33 further comprising during said conveying, maintaining a substantially uniform liquid flow field transverse to the direction of movement of the PCBWP through the chemical treatment liquid. 
     
     
       36. The method of claim 33 wherein said lifting includes lifting the PCBWP while in the substantially vertical orientation. 
     
     
       37. The method of claim 36 further comprising after said lifting, flipping the PCBWP over to a substantially horizontal orientation. 
     
     
       38. The method of claim 37 further comprising after said flipping, conveying the PCBWP generally away from the bath. 
     
     
       39. A method of chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said method comprising the steps of: repositioning a PCBWP from a horizontal orientation to a substantially vertical orientation in a chemical treatment liquid bath and onto a conveyor belt submerged in the bath;   conveying via the conveyor belt the PCBWP in the substantially vertical orientation face-on through the bath along a line substantially perpendicular to the plane of the PCBWP;   after said conveying, lifting the PCBWP out of the bath; and   wherein said repositioning includes allowing the PCBWP to fall and sink by itself edge-wise in the bath of its own weight onto the conveyor belt.   
     
     
       40. A method of chemically treating surfaces of a panel-like planar printed circuit board work piece (PCBWP), said method comprising the steps of: repositioning a PCBWP from a horizontal orientation to a substantially vertical orientation in a chemical treatment liquid bath and onto a conveyor belt submerged in the bath;   conveying via the conveyor belt the PCBWP in the substantially vertical orientation face-on through the bath along a line substantially perpendicular to the plane of the PCBWP;   after said conveying, lifting the PCBWP out of the bath; and   wherein said lifting includes lifting with a substantially vertical endless belt conveyor.   
     
     
       41. The method of claim 40 wherein the substantially vertical belt conveyor has a plurality of holders, and said lifting includes holding a lower end of the PCBWP in one of the holders.